As the light efficiency of LCDs is relatively low, low brightness of the LCDs has been a problem bothering many designers. With the development of technologies, many solutions have been proposed with an aim of solving the problem, some of which achieved quite good effect, such as Brightness Enhancement Film (BEF). In BEF, a lot of prisms with the same configuration disposed on the BEF surface makes light of the backlight system to concentrate to the front of a user by reflection and refraction. Two BEFs having orthogonal prisms may improve the visual brightness by over 100%. Another solution is Dual-Brightness Enhancement Film (DBEF), which reflects light having a polarization direction vertical to the grid direction of a lower polarizer of the liquid crystal panel back to a light guide plate (LGP) through several layer of films, while allows light having the same polarization direction as the grid direction of the lower polarizer of the liquid crystal to pass. In the method, after the reflected light undergoes multiple reflections and refractions in the LGP, a part of the light has its vibration direction changed to the grid direction parallel with the polarizer and enters the liquid crystal layer again through the lower polarizer. However, the backlight sources in conventional technologies have a problem of optical energy being scattered. To improve the light efficiency, it is desirable that optical energy be concentrated in the vertical direction to the greatest extent.